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Division Spotlight
Isotopes & Radiation
Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
Meeting Spotlight
2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Nuclear Science and Engineering
October 2024
Nuclear Technology
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Latest News
PNNL seeks high-energy neutrons from SpaceX launch of Polaris Dawn
When a SpaceX rocket lifted off from Kennedy Space Center on September 10 (see video here), sending a crewed commercial mission into low Earth orbit, an experiment designed by Pacific Northwest National Laboratory was onboard. Several high-purity metal samples will orbit Earth and absorb cosmic radiation for five days—including that from the Van Allen radiation belt—to help the lab answer questions about the radiation environment for manned space missions, according to a news release from PNNL.
Miriam A. Kreher, Kord Smith, Benoit Forget
Nuclear Science and Engineering | Volume 196 | Number 4 | April 2022 | Pages 409-432
Technical Paper | doi.org/10.1080/00295639.2021.1980363
Articles are hosted by Taylor and Francis Online.
Transient simulations of nuclear systems face the computational challenge of resolving both space and time during reactivity changes. A common strategy for tackling this issue is to split the neutron flux into shape and amplitude functions. This split can be solved with high-order/low-order methods. In this paper, a direct comparison of commonly used approximations (e.g., adiabatic, omega, alpha eigenvalue, frequency transform, quasi-static) is performed on the two-dimensional Laboratorium für Reaktorregelung und Anlagensicherung (2D-LRA) benchmark problem using a diffusion solver as the high-order solver and point kinetics as the low-order solver. Additionally, a novel hybrid omega/alpha-eigenvalue solver that incorporates frequencies to model delayed neutrons is introduced. The goal of the comparison is to quantify the performance of each method on a common problem to help inform promising pathways for costly high-fidelity solvers. Overall, we show that exponential frequency approximations are an effective strategy for increasing the accuracy of transient simulations with no added cost. Root-mean-square error of the power distribution at the peak of the transient was consistently decreased by 20% by including frequencies. In particular, the hybrid omega/alpha-eigenvalue method shows improvement over existing eigenvalue solvers as a high-order method. However, in our implementation, the cost of solving for the alpha eigenmode is too costly to recommend over the omega method. While time-differencing schemes are more accurate, we believe the eigenvalue methods are more adaptable to further applications in Monte Carlo transients. Furthermore, they required fewer outer time steps, significantly reducing the computational cost.